Internal member of a plasma processing vessel

ABSTRACT

An internal member of a plasma processing vessel includes a base material and a film formed by thermal spraying of ceramic on a surface of the base material. The film is formed of ceramic which includes at least one kind of element selected from the group consisting of B, Mg, Al, Si, Ca, Cr, Y, Zr, Ta, Ce and Nd. In addition, at least a portion of the film is sealed by a resin.

FIELD OF THE INVENTION

The present invention relates to an internal member of a plasmaprocessing vessel; and, more particularly, to an internal member of aplasma processing vessel, for example, a deposition shield, an exhaustplate, a focus ring, an electrode plate, an electrostatic chuck, aninner wall member of a processing vessel and the like, for use in aplasma processing vessel in which a plasma atmosphere of a processinggas including a halogen element is formed.

BACKGROUND OF THE INVENTION

Processes of manufacturing a semiconductor, a liquid crystal device andthe like generally employ a plasma process using a plasma, wherein aninternal member of a processing vessel tends to be considerably corrodedand worn out because a gas including a halogen element, e.g., a fluoridesuch as C₄F₈ or NF₃, a chloride such as BCl₃ or SnCl₄, and a bromidesuch as HBr, is used in the processing vessel. Therefore, strong plasmaresistance is needed in internal members of the plasma processingvessel, such as a deposition shield, an exhaust plate, a focus ring, anelectrode plate, an electrostatic chuck, an inner wall of the processingvessel and the like.

In conjunction with this, there is disclosed a technique for improvingplasma resistivity of the internal member of the processing vessel byforming a thermally sprayed film with a highly corrosion resistantmaterial such as Al₂O₃ or Y₂O₃ on a surface of a base material made ofAl, Al alloy, Al oxide, quartz or the like (see, e.g., reference patent1). Further, an anodic oxidized film may be formed between the basematerial and the thermally sprayed film. Furthermore, in order toimprove adhesivity of the thermally sprayed film, the surface of thebase material or the anodic oxidized film can be roughened intentionallyby using blast processing or the like to prevent the thermally sprayedfilm from being peeled off by anchor effect.

In case of the above-mentioned plasma etching processing apparatus,cleaning by a cleaning fluid of pure water, fluorine-based solvent ororganic solvent such as acetone is performed on a regular basis toremove a reaction by-product attached to inside of the processing vesselin addition to using the processing gas including a highly corrosivehalogen element. In this case, the processing gas and the cleaning fluidfor cleaning may permeate into a space between the base material and thethermally sprayed film or between the base material and the anodicoxidized film to thereby generate a corrosion by-product on the surfaceof the base material by reaction of the gas and the cleaning fluid,resulting in peeling off of the thermally sprayed film.

In other words, in an internal member of a plasma processing vessel 100,as shown in FIG. 21A, a reaction by-product 103 such as CF polymer isdeposited on a surface of a thermally sprayed film 102 on a basematerial 101 such as Al, but the reaction by-product 103 is removedregularly or irregularly, as shown in FIG. 21B among FIGS. 21A to 21D,by immersing it in a given cleaning fluid 104 or by another method.Then, as shown in FIG. 21C, a processing gas, a cleaning fluid, or afluid reacted with the reaction by-product infiltrates into air pores ofthe thermally sprayed film 102, a boundary between the sprayed film 102and the base material 101, or a portion damaged by plasma, the gas andthe like to reach the surface of the base material 101. Theaforementioned phenomenon is considered to cause the corrosionby-product to be formed on the surface of the base material 101 or theloss of anchor effect by smoothing the surface of the base materialroughened to obtain the anchor effect, thus resulting in a portion 105of the thermally sprayed film 102 being peeled off from the basematerial 101, as shown in FIG. 21D.

The above-mentioned Al₂O₃ and Y₂O₃ have high reactivity on water in theair and when they are used as the inner wall member of the processingvessel and the like, it is possible that a vacuum chamber, theprocessing vessel, may absorb plenty of water when it is open to theatmosphere or undergoes wet cleaning. And, the abundantly absorbed waterin the chamber will be released from the inner wall of the vacuumchamber during process due to high temperature in the vacuum chamber orplasma discharge, which in turn will have adverse effects on theprocess, such as particle production by chemical reaction of the waterwith deposits or the inner wall of the vacuum chamber, a prolongedvacuum exhaust time, abnormal electricity discharge, and deteriorationof film forming properties.

In this regard, reference patent 2 discloses a method for performing thevacuum exhaust in a short time, wherein a plasma produced is made tocontact with the inner wall surface of a plasma producing chamber duringa vacuum exhaust process in such a way that temperature of the innerwall is raised to thereby vaporize the adhered water molecules. Further,in reference patent 3, there is presented a technique in which a heateris installed in a lid member of a vacuum chamber and controlled to keepan inner wall of the vacuum chamber at a specified or at a highertemperature all the time during plasma treatment, so that the amount ofwater and organic matter adsorbed to the inner wall of the vacuumchamber is reduced and, at the same time, the adsorbed water and theorganic matter are rapidly vaporized. Furthermore, in reference patents4 and 5, there is offered a technique in which a removable shield memberis installed on an inner wall of a vacuum chamber and instruction forcleaning and replacement of shield member is indicated when the timeneeded to reach a vacuum state exceeds a set time.

The techniques of the reference patents 2 to 5, however, cannot give afundamental solution to the problems and the effect thereof is limitedsince all of them are dealing the situation after water is adsorbed.

reference patent 1: Japanese Patent Laid-Open Publication No. 8-339895(page 3, FIG. 2)

reference patent 2: Japanese Patent Laid-Open Publication No. 8-181117

reference patent 3: Japanese Patent Laid-Open Publication No. 11-54484

reference patent 4: Japanese Patent Laid-Open Publication No. 11-54487

reference patent 5: Japanese Patent Laid-Open Publication No.2002-124503

SUMMARY OF THE INVENTION

The present invention has been developed to solve the aforementionedproblems in the conventional techniques. An object of the presentinvention is to provide a new, improved internal member of a plasmaprocessing vessel capable of suppressing peeling off of a thermallysprayed film formed as a top coat layer.

Further, another object is to provide an internal member of a plasmaprocessing vessel in which release of water in the plasma process ismade difficult to occur.

In order to solve the above problems, in accordance with a first aspectof the present invention, there is provided an internal member of aplasma processing vessel including a base material and a film formed bythermal spraying of ceramic on a surface of the base material, whereinthe film is formed of ceramic including at least one kind of elementselected from the group consisting of B, Mg, Al, Si, Ca, Cr, Y, Zr, Ta,Ce and Nd, and at least a portion of the film is sealed by a resin.

In accordance with a second aspect of the present invention, there isprovided an internal member of a plasma processing vessel including abase material and a film formed by thermal spraying of ceramic on asurface of the base material, wherein the film has a first ceramic layerformed of ceramic including at least one kind of element selected fromthe group consisting of B, Mg, Al, Si, Ca, Cr, Y, Zr, Ta, Ce and Nd anda second ceramic layer formed of ceramic including at least one kind ofelement selected from the group consisting of B, Mg, Al, Si, Ca, Cr, Y,Zr, Ta, Ce and Nd, and at least a portion of at least one of the firstand the second ceramic layer is sealed by a resin.

In accordance with the first and the second aspect of the presentinvention, it is preferable that the resin is selected from the groupconsisting of SI, PTFE, PI, PAI, PEI, PBI and PFA.

In accordance with a third aspect of the present invention, there isprovided an internal member of a plasma processing vessel including abase material and a film formed by thermal spraying of ceramic on thesurface of the base material, wherein the film is formed of ceramicincluding at least one kind of element selected from the groupconsisting of B, Mg, Al, Si, Ca, Cr, Y, Zr, Ta, Ce and Nd, and at leasta portion of the film is sealed by a sol-gel method.

In accordance with a fourth aspect of the present invention, there isprovided an internal member of a plasma processing vessel including abase material and a film formed by thermal spraying of ceramic on asurface of the base material, wherein the film has a first ceramic layerformed of ceramic including at least one kind of element selected fromthe group consisting of B, Mg, Al, Si, Ca, Cr, Y, Zr, Ta, Ce and Nd anda second ceramic layer made of ceramic including at least one elementselected from the group consisting of B, Mg, Al, Si, Ca, Cr, Y, Zr, Ta,Ce and Nd, and at least a portion of at least one of the first and thesecond ceramic layer is sealed by a sol-gel method.

In accordance with the third and the fourth aspect of the presentinvention, it is preferable that the sealing treatment is executed byusing an element of the Group 3a in the periodic table.

In accordance with the first to the fourth aspect of the presentinvention, the ceramic may be at least one kind of ceramic selected fromthe group consisting of B₄C, MgO, Al₂O₃, SiC, Si₃N₄, SiO₂, CaF₂, Cr₂O₃,Y₂O₃, YF₃, ZrO₂, TaO₂, CeO₂, Ce₂O₃, CeF₃ and Nd₂O₃.

In accordance with a fifth aspect of the present invention, there isprovided an internal member of a plasma processing vessel including abase material and a film formed on a surface of the base material,wherein the film has a main layer formed by thermal spraying of ceramicand a barrier coat layer formed of ceramic including an element selectedfrom the group consisting of B, Mg, Al, Si, Ca, Cr, Y, Zr, Ta, Ce andNd.

In accordance with the fifth aspect of the present invention, thebarrier coat layer may be formed of at least one kind of ceramicselected from the group consisting of B₄C, MgO, Al₂O₃, SiC, Si₃N₄, SiO₂,CaF₂, Cr₂O₃, Y₂O₃, YF₃, ZrO₂, TaO₂, CeO₂, Ce₂O₃, CeF₃ and Nd₂O₃.Further, the barrier coat layer may be a thermally sprayed film at leasta portion of which is sealed by a resin, and it is preferable that theresin is selected from the group consisting of SI, PTFE, PI, PAI, PEI,PBI and PFA. Furthermore, the barrier coat layer may be a thermallysprayed film at least a portion of which is sealed by a sol-gel method,and it is preferable that the sealing treatment is executed by using anelement of the Group 3a in the periodic table.

In accordance with a sixth aspect of the present invention, there isprovided an internal member of a plasma processing vessel including abase material and a film formed on a surface of the base material,wherein the film has a main layer formed by thermal spraying of ceramicand a barrier coat layer formed of an engineering plastic between thebase material and the main layer.

In accordance with the sixth aspect of the present invention, theengineering plastic may be selected from the group consisting of PTFE,PI, PAI, PEI, PBI, PFA, PPS and POM.

In accordance with the fifth and sixth aspects of the present invention,the main layer may be formed of at least one kind of ceramic selectedfrom the group consisting of B₄C, MgO, Al₂O₃, SiC, Si₃N₄, SiO₂, CaF₂,Cr₂O₃, Y₂O₃, YF₃, ZrO₂, TaO₂, CeO₂, Ce₂O₃, CeF₃ and Nd₂O₃.

In accordance with a seventh aspect of the present invention, there isprovided an internal member of a plasma processing vessel including abase material and a film formed on a surface of the base material,wherein the film is formed of ceramic including at least one element ofthe Group 3a in the periodic table, and at least a portion of the filmis hydrated by vapor or high temperature hot water.

In accordance with an eighth aspect of the present invention, there isprovided an internal member of a plasma processing vessel including abase material and a film formed on a surface of the base material,wherein the film has a first ceramic layer formed of ceramic includingat least one kind of element of the Group 3a in the periodic table and asecond ceramic layer formed of ceramic including at least one kind ofelement of the Group 3a in the periodic table, and at least a portion ofat least one of the first and the second ceramic layer is hydrated byvapor or high temperature hot water.

In accordance with the seventh and eighth aspects of the presentinvention, the film is a thermally sprayed film formed by thermalspraying or a thin film formed by employing a technique for forming athin-film. Further, it is preferable that the film is formed of ceramicis selected from Y₂O₃, CeO₂, Ce₂O₃ and Nd₂O₃.

In accordance with a ninth aspect of the present invention, there isprovided an internal member of a plasma processing vessel including abase material and a film formed on a surface of the base material,wherein the film has a first ceramic layer formed of ceramic includingat least one kind of element of the Group 3a in the periodic table and asecond ceramic layer formed by thermal spraying of ceramic, and at leasta portion of the first ceramic layer is hydrated by vapor or hightemperature hot water.

In accordance with the ninth aspect of the present invention, athermally sprayed film formed by thermal spraying or a thin film formedby employing a technique for forming a thin film can be used as thefirst ceramic layer. Further, it is preferable that the first ceramiclayer is formed of ceramic selected from Y₂O₃, CeO₂, Ce₂O₃ and Nd₂O₃.Furthermore, it is preferable that the second ceramic layer is formed ofat least one kind of ceramic selected from the group consisting of B₄C,MgO, Al₂O₃, SiC, Si₃N₄, SiO₂, CaF₂, Cr₂O₃, Y₂O₃, YF₃, ZrO₂, TaO₂, CeO₂,Ce₂O₃, CeF₃ and Nd₂ O₃.

In accordance with a tenth aspect of the present invention, there isprovided an internal member of a plasma processing vessel including abase material and a film formed on a surface of the base material,wherein the film has a hydroxide layer formed of a hydroxide includingat least one kind of element of the Group 3a in the periodic table.

In accordance with the tenth aspect of the present invention, athermally sprayed film formed by thermal spraying or a thin film formedby employing a technique for forming a thin film can be used as thehydroxide layer. Further, it is preferable that the hydroxide layer isformed of hydroxide selected from Y(OH)₃, Ce(OH)₃ and Nd(OH)₃.Furthermore, at least a portion of the hydroxide layer may be sealed.

In accordance with the first to tenth aspects of the present invention,an anodic oxidized film may be formed between the base material and thefilm, and in this case, it is preferable that the anodic oxidized filmis sealed by an aqueous solution of metal salt.

In accordance with an eleventh aspect of the present invention, there isprovided an internal member of a plasma processing vessel, which isformed of a sintered ceramic body including at least one kind of elementof the Group 3a in the periodic table, wherein at least a portion of thesintered ceramic body is hydrated by vapor or high temperature hotwater. In this case, it is preferable that the sintered ceramic body isformed by hydrating of ceramic selected from Y₂O₃, CeO₂, Ce₂O₃ andNd₂O₃.

In accordance with a twelfth aspect of the present invention, there isprovided an internal member of a plasma processing vessel, which isformed of a sintered ceramic body including hydroxide including at leastone kind of element of the Group 3a in the periodic table. In this case,it is preferable that the sintered ceramic body includes hydroxideselected from Y(OH)₃, Ce(OH)₃ and Nd(OH)₃.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross-sectional view of a plasma etching apparatusin which an internal member of a plasma processing vessel in accordancewith preferred embodiments of the present invention is installed;

FIG. 2 shows a cross sectional view of a layer structure of a firstexample of an internal member of a plasma processing vessel inaccordance with a first embodiment of the present invention;

FIG. 3 shows a cross sectional view of an example in which an anodicoxidized film is added to the structure of FIG. 2;

FIGS. 4A to 4C depict cross sectional views of layer structures of asecond example of the internal member of the plasma processing vessel inaccordance with the first embodiment of the present invention;

FIG. 5 depicts a cross sectional view of an example in which the anodicoxidized film is added to the structures of FIGS. 4A to 4C;

FIGS. 6A and 6B describe cross sectional views of layer structures of athird example of the internal member of the plasma processing vessel inaccordance with the first embodiment of the present invention;

FIG. 7 describes a cross sectional view of an example in which theanodic oxidized film is added to the structures of FIGS. 6A and 6B;

FIG. 8 illustrates a cross sectional view of a layer structure of afirst example of an internal member of a plasma processing vessel inaccordance with a second embodiment of the present invention;

FIGS. 9A and 9B illustrate drawings comparing patterns of X-ray analysisof a case where hydration treatment is executed on a Y₂O₃ film and acase where the hydration treatment is not executed;

FIG. 10 illustrates drawings comparing adsorption of IPA of a case wherethe hydration treatment is executed on the Y₂O₃ film and a case wherethe treatment is not executed;

FIGS. 11A to 11C illustrate drawings comparing penetrations into resinof a case where the hydration treatment is executed on the Y₂O₃ film anda case where the treatment is not executed;

FIGS. 12A and 12B are photographs of a scanning electron microscopeshowing layer states before and after the hydration treatment;

FIG. 13 illustrates a cross sectional view of an example in which ananodic oxidized film is added to the structure of FIG. 8;

FIGS. 14A and 14B show cross sectional views of layer structures of asecond example of the internal member of the plasma processing vessel inaccordance with the second embodiment of the present invention;

FIG. 15 shows a cross sectional view of an example in which the anodicoxidized film is added to the structures of FIGS. 14A and 14B;

FIG. 16 depicts a cross sectional view of a layer structure of a thirdexample of the internal member of the plasma processing vessel inaccordance with the second embodiment of the present invention;

FIG. 17 depicts a cross sectional view of a layer structure of the thirdexample of the internal member of the plasma processing vessel inaccordance with the second embodiment of the present invention;

FIG. 18 depicts a cross sectional view of a layer structure of the thirdexample of the internal member of the plasma processing vessel inaccordance with the second embodiment of the present invention;

FIG. 19 describes a cross sectional view of an example in which theanodic oxidized film is added to the structure of FIG. 16;

FIG. 20 illustrates a diagram of an internal member of a plasmaprocessing vessel in accordance with a third embodiment of the presentinvention; and

FIGS. 21A to 21D illustrate a diagrammatic drawing showing states ofpeeling off of a thermally sprayed film (a top coat layer) in aconventional internal member of a plasma processing vessel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the preferred embodiments of the present invention will bedescribed in detail.

FIG. 1 is a vertical cross-sectional view of an example of a plasmaetching processing apparatus, which is a plasma processing apparatuswith an internal member of a plasma processing vessel, a subject of thepresent invention. A reference numeral 2 refers to a vacuum chamberincluded in the processing vessel, which is formed of a conductivematerial, such as aluminum, to have an airtight structure. And thevacuum chamber 2 is frame-grounded. Additionally, a cylindricaldeposition shield 2 a is disposed to an inner surface of the vacuumchamber 2 to prevent the inner surface from being damaged by plasma.Further, disposed in the vacuum chamber 2 are a gas shower head 3serving also as an upper electrode and a mounting table 4 serving alsoas a lower electrode, which are installed to face each other. Andconnected to a lower surface is an exhaust pipe 22, which serves as avacuum exhaust passageway communicating with a vacuum exhaust unit 21having, e.g., a turbo molecular pump or a dry pump. Furthermore, anopening 23 for charging or discharging an object to be processed, e.g.,a semiconductor wafer W, is formed on a sidewall portion of the vacuumchamber 2 and it can be opened or closed by a gate valve G. Permanentmagnets 24 and 25, having, for example, a shape of ring, are mounted onan outside of a sidewall portion in such a manner that the opening 23 islocated therebetween.

The gas shower head 3 has a plural number of holes 31 facing the objectW to be processed on the mounting table 4, and is configured to supply aflow-controlled or pressure-controlled processing gas coming from anupper gas supply line 32 to a surface of the object W to be processeduniformly through the corresponding holes 31.

Disposed under the gas shower head 3 from about 5 mm to 150 mm aparttherefrom, the mounting table 4 includes a cylindrical main body 41which is formed of, for example, aluminum having its surface subjectedto alumite treatment and is insulated by an insulating member 41 a fromthe vacuum chamber 2; an electrostatic chuck 42 mounted on an uppersurface of the main body 41; a circular focus ring 43 surrounding theelectrostatic chuck 42; and an insulation ring 43 a as a circularinsulation member inserted between the focus ring 43 and the main body41. Further, depending on a process, an insulating or conductivematerial is selected for the focus ring 43 to confine or diffusereactive ions.

In the mounting table 4, for example, the body 41 thereof is connectedto a high frequency power supply 40 via a capacitor C1 and a coil L1,and a high frequency power in a range of, e.g., from 13.56 MHz to 100MHz is applied thereto.

Moreover, installed inside the mounting table 4 are a temperaturecontrol unit 55 a of a cooling jacket and a heat transfer gas supplyunit 55 b to supply, e.g., He gas to a rear surface of the object W tobe processed. A process surface of the object W to be processed, held onthe mounting table 4, can be maintained at a desired temperature byactivating the temperature control unit 55 a and the heat transfer gassupply unit 55 b. The temperature control unit 55 a has an inlet line 56and a discharge line 57 for circulating a coolant via the coolingjacket. The coolant regulated to be kept at an adequate temperature isprovided into the cooling jacket by the inlet line 56, and the coolantafter heat exchange is exhausted to outside by the discharge line 57.

A ring-shaped exhaust plate 44 having a plurality of exhaust holespunched therein is disposed between the mounting table 4 and the vacuumchamber 2 and installed at a position lower than a surface of themounting table 4 in such a manner that it surrounds the mounting table4. The exhaust plate 44 serves to optimally confine the plasma betweenthe mounting table 4 and the gas shower head 3 and to regulate flows ofexhaust current are regulated. Additionally, protrudently installed inthe mounting table 4 are a plural number, for example, three, ofelevating pins 51 (only two pins are shown) as elevating members forexecuting transfer of the object W to be processed between an externaltransfer arm (not shown) and the mounting table 4 such that theelevating pins 51 can be elevated and lowered by a driving unit 53through a coupling member 52. A reference numeral 54 refers to a bellowsfor keeping the space between through holes of the elevating pins 51 andthe atmosphere airtight.

In the plasma etching processing apparatus, after being transferred intothe vacuum chamber 2 via the gate valve G and the opening 23, the objectW to be processed is first mounted on the electrostatic chuck 42, thegate valve (G) is closed, and an inside of the vacuum chamber 2 isexhausted through the exhaust pipe 22 by the vacuum exhaust unit 21 to apredetermined degree of vacuum. Thereafter, when the processing gas issupplied to the inside of the vacuum chamber 2, a DC voltage issimultaneously applied from a DC power supply 47 to a chuck electrode46, so that the object W to be processed is electrostatically attractedto be held by the electrostatic chuck 42. Under the condition, the highfrequency power with a predetermined frequency is applied from the highfrequency power supply 40 to the main body 41 of the mounting table 4 tothereby generate a high frequency electric field between the gas showerhead 3 and the mounting table 4, which in turn transforms the processinggas into plasma used for performing an etching process on the object Wto be processed on the electrostatic chuck 42.

As the processing gas, a gas including a halogen element, for example, afluoride such as C₄F₈ and NF₃, a chloride such as BCl₃ and SnCl₄, and abromide such as HBr, is used. Since a highly strong corrosiveenvironment is generated inside the vacuum chamber 2 owing to this, astrong plasma resistance is imperatively required for the members withinthe vacuum chamber 2, that is, the internal members of the plasmaprocessing vessel, for example, the deposition shield 2 a, the exhaustplate 44, the focus ring 43, the shower head 3, the mounting table 4,the electrostatic chuck 42, and the inner wall member of the vacuumchamber 2.

Hereinafter, the internal member of the processing vessel as a subjectof the present invention will be described in detail.

Embodiment 1

In a conventional case where a base material having a thermally sprayedfilm formed thereon a base material is used as an internal member of aprocessing vessel, a thermally sprayed film is bound to be peeled off.The present inventors have found in their investigation that the peelingoff of the thermally sprayed film on the internal member of the plasmaprocessing vessel is resulted from the fact that the processing gasand/or the cleaning fluid infiltrate through air pores (fine holes) ofthe thermally sprayed film, a boundary portion between the thermallysprayed film and the base material or a portion damaged by plasma andgas to thereby reach the base material, which ultimately corrodes asurface of the base material.

In other words, if a member of a processing vessel, where a plasmatreatment has been performed by using a processing gas including afluoride, is prepared to analyze a boundary surface (a base materialsurface) between the base material and the thermally sprayed film, F(fluorine) can be found therein. From this, it is suggested that Freacts on water (OH) to form HF, whereby the base material surface iscorrosively changed (a corrosion by-product is generated), which leadsto the peeling off of the thermally sprayed film.

Therefore, it is important that the boundary surface between the basematerial and the thermally sprayed film, i.e., the base materialsurface, is not exposed to the processing gas or the cleaning fluid.

Based on the aforementioned facts, in a first embodiment, a portionhaving barrier function which is hardly corroded is formed at a positionbetween the surface of the sprayed film and the base material in themembers within the vacuum chamber 2, i.e., the internal members of theplasma processing vessel, for example, the deposition shield 2 a, theexhaust plate 44, the focus ring 43, the shower head 3, the mountingtable 4, the electrostatic chuck 42 and the inner wall member of thevacuum chamber 2 shown in FIG. 1, even if it is exposed to theprocessing gas or the cleaning fluid, thus being capable of preventingthe processing gas or the cleaning fluid from reaching the surface ofthe base material.

By forming the portion having the barrier function by using a highcorrosion-resistant material, the surface of the base material can beprotected from the processing gas or the cleaning fluid infiltratingthrough the air pores (the fine holes) of the thermally sprayed film.Additionally, if the portion having the barrier function is in contactwith the base material, employing a material with high adhesivity forthe portion makes it possible to protect the surface of the basematerial from infiltration of the processing gas or the cleaning fluidthrough a boundary surface between the portion having the barrierfunction and the surface of the base material.

Hereinafter, a concrete structure in accordance with the firstembodiment will be described in detail.

First, as shown in FIG. 2, the internal member of the plasma processingvessel in accordance with the first example basically includes a basematerial 71 and a film 72 formed on its surface. The film 72 has a mainlayer 73 formed by thermal spraying and a barrier coat layer 74 formedbetween the base material 71 and the main layer, which has the barrierfunction to be rarely corroded even when exposed to the processing gasor the cleaning fluid.

Various types of steel including stainless steel (SUS), Al, Al alloy, W,W alloy, Ti, Ti alloy, Mo, Mo alloy, carbon, oxide or non-oxide basedsintered ceramic body, carbonaceous material and the like are usedproperly for the base material 71 as an object on which the film 72 isconstructed.

It is preferable that the barrier coat layer 74 is formed of ceramicincluding at least one kind of element selected from the groupconsisting of B, Mg, Al, Si, Ca, Cr, Y, Zr, Ta, Ce and Nd, and, moreparticularly, at least one kind of ceramic selected from the groupconsisting of B₄C, MgO, Al₂O₃, SiC, Si₃N₄, SiO₂, CaF₂, Cr₂O₃, Y₂O₃, YF₃,ZrO₂, TaO₂, CeO₂, Ce₂O₃, CeF₃ and Nd₂O₃. For example, products of TOCALOco., LTD. such as “CDC-ZAC” and “super ZAC” are applicable. “CDC-ZAC” isa complex ceramic including Cr₂O₃ as a main ingredient, and has featuressuch as imporosity, high hardness, high adhesion and the like. On theother hand, super ZAC is a complex ceramic including SiO₂ and Cr₂O₃ asmain ingredients, and has excellent heat-resistance andabrasion-resistance in addition to imporosity, high hardness and highadhesion. It is preferable to form the barrier coat layer 74 by athermal spraying method. The thermal spraying method is a method forspraying raw material melted by a heat source such as combustion gas andelectricity on a basic material to form a film. Further, the barrierlayer 74 may be formed by employing a technique for forming a thin-filmsuch as PVD and CVD method, an immersion method, a coating method, orthe like. The PVD method is a method of coating various ceramic filmscoated at low temperature by employing an ion plating method, while theCVD method is a method for coating single layer or multiple layers athigh temperature by a thermal chemical vapor deposition. Furthermore,the method is a method for performing a heat treatment after immersingvarious materials being immersed into a resin solution, and the coatingmethod is a method for performing the heat treatment at a predeterminedtemperature after various materials being coated with a resin solution.It is desirable that the barrier coat layer 74 is of a thickness rangingfrom 50 to 100 μm.

In this case, it is preferable to perform sealing by using a resin on atleast one portion of the barrier coat layer 74, e.g., on a surfacecontacted with the base material 71, or on the whole of the barrier coatlayer 74. It is desirable that the resin is selected from the groupconsisting of SI, PTFE, PI, PAI, PEI, PBI and PFA. That is, the barriercoat layer 74 made of ceramic has porosity with air pores (fine holes)when forming by using the aforementioned thermal spraying method, butsealing the fine holes in at least a portion of the porous layer withthe resin can prevent the gas or the cleaning fluid from infiltratingthrough the fine holes of the main layer 73 made of the thermallysprayed film, thus protecting the base material 71 effectively.

Additionally, SI refers to silicon, PTFE to polytetrafluoroethylene, PIto polyimide, PAI to polyamideimide, PEI to polyetherimide, PBI topolybenzimidazole, and PFA to perfluoroalkoxyalkane.

The sealing treatment may be executed by employing a sol-gel method. Thesealing treatment employing the sol-gel method is performed by sealingwith a sol (a colloidal solution) in which ceramic is dispersed in anorganic solvent, and then by the gelation by heating. Accordingly, thesealing by using ceramic is substantialized, so that a barrier effectcan be improved. It is preferable that a material selected from theelements of the Group 3a in the periodic table is used in the sealingtreatment of this case. Among them, highly corrosion-resistant Y₂O₃ isdesirable.

Moreover, engineering plastics may be used as another alternativematerial for the barrier coat layer 74. Specifically, a resin selectedfrom the group consisting of PTFE, PI, PAI, PEI, PBI, PFA, PPS and POMis preferable and, for example, “Teflon (a registered trademark)”(PTFE), a product of DUPONT INC., and the like are applicable. Theseresins have excellent adhesivity and chemical resistance which aresufficient enough to stand against the cleaning fluid in cleaning.

Further, PTFE refers to polytetrafluoroethylene, PI to polyimide, PAI topolyamideimide, PEI to polyetherimide, PBI to polybenzimidazole, PFA toperfluoroalkoxyalkane, PPS to polyphenylenesulfide, and POM topolyacetal.

Furthermore, an anodic oxidized film 75 may be formed between the basematerial 71 and the barrier coat layer 74 as depicted in FIG. 3. In thiscase, it is desirable that the anodic oxidized film is formed by organicacid, such as oxalic acid, chromic acid, phosphoric acid, acetic acid,formic acid or sulfonic acid, which will result in an oxidized filmwhose corrosion resistance is much better than those produced by ananodic oxidation treatment by sulfuric acid, so that it can furthersuppress the corrosion by the processing gas and the cleaning fluid. Itis preferable that the anodic oxidized film 75 is of a thickness rangingfrom 10 to 200 μm.

As described above, in case the anodic oxidized film 75 is formedbetween the base material 71 and the barrier coat layer 74, sealing fineholes of the anodic oxidized film 75 can markedly improve corrosionresistance. In this case, a metal salt sealing is applicable, in which amaterial is immersed in hot water including metal salt such as Ni, sothat, in fine holes of the oxidized film, an aqueous solution of metalsalt is hydrolyzed, whereby hydroxide is precipitated, thus performingsealing. Further, the same effect can also be achieved even when thesealing treatment of the fine holes of the anodic oxidized film 75 isexecuted by using the resin (selected from the group consisting of SI,PTFE, PI, PAI, PEI, PBI and PFA) used in the sealing treatment of thebarrier coat layer 74.

Furthermore, an anodic oxidized film (KEPLA-COAT a registered trademark)with a porous ceramic layer may be used as the anodic oxidized film 75formed on the surface of the base material 71.

Further, the anodic oxidized film (KEPLA-COAT) is formed by immersingthe base material as an anode in an alkali-based organic electrolyte todischarge an oxygen plasma therein.

It is preferable that the main layer 73 as the thermally sprayed filmincludes at least one kind of element selected from the group consistingof B, Mg, Al, Si, Ca, Cr, Y, Zr, Ta, Ce and Nd, and, to be morespecific, it is preferable to include at least one kind of ceramicselected from the group consisting of B₄C, MgO, Al₂O₃, SiC, Si₃N₄, SiO₂,CaF₂, Cr₂O₃, Y₂O₃, YF₃, ZrO₂, TaO₂, CeO₂, Ce₂O₃, CeF₃ and Nd₂O₃.

In this case, it is desirable that the main layer 73 is of a thicknessranging from 10 to 500 μm.

When the internal members of the plasma processing vessel with thesestructures are fabricated, it is preferable to increase adhesivity ofthe barrier coat layer 74 or the anodic oxidized film 75 to be formed onthe surface of the base material 71 by executing a blast treatment forblowing up particles such as Al₂O₃, SiC or sand on the surface of thebase material 71 to make the surface thereof microscopically uneven.Additionally, etching the surface, e.g., by immersion in a givenmedicinal fluid, is allowed as a method for making the surface uneven,not limiting the method to the aforementioned blast treatment.

Next, the aforementioned barrier coat layer 74 is formed directly on thebase material 71 or through the anodic oxidized film 75 by employing thethermal spraying method or another proper method. If necessary, thesealing treatment as described above is executed. When the sealingtreatment is performed, the aforementioned resin or sol of ceramic iscoated on the surface of the barrier coat layer 74, or the base material71 with the barrier coat layer 74 thereon is immersed in a resin sealingmaterial or the sol of ceramic. In case the sealing is performed by thesol of ceramic, gelation by heating is followed by heating.

After forming the barrier coat layer 74, the main layer 73, a thermallysprayed film, is sequentially formed, wherein the layer is formed of atleast one kind of ceramic selected from the group consisting of B₄C,MgO, Al₂O₃, SiC, Si₃N₄, SiO₂, CaF₂, Cr₂O₃, Y₂O₃, YF₃, ZrO₂, TaO₂, CeO₂,Ce₂O₃, CeF₃ and Nd₂O₃. In addition to selecting a material withexcellent adhesivity as the barrier coat layer 74, the blast process andthe like may be performed on the surface of the barrier coat layer 74 tofurther improve adhesivity with the main layer 73.

As described above, in this example, the problem that the thermallysprayed film 72 on the base material 71 is peeled off by generation ofthe corrosion by-product on the surface of the base material 71 can besolved by forming the barrier coat layer 74 made of material withexcellent corrosion resistance against the processing gas including thehalogen element or the cleaning fluid between the main layer 73 as thethermally sprayed film and the base material 71 in such a way that thesurface of the base material 71 is not exposed to the processing gas(halogen element) or the cleaning fluid.

Hereinafter, a second example will be described.

In the second example, as shown in FIGS. 4A, 4B and 4C, a film 76 isformed on the surface of the base material 71 by thermal spraying ofceramic and a sealing-treated portion 76 a is formed in at least aportion of the film 76. The sealing-treated portion 76 a is formed in aside of a portion of the film 76 making a contact with the base material71 in an example of FIG. 4A, in a surface side of the film 76 in theexample of FIG. 4B, and in the whole of the film 76 in the example ofFIG. 4C, respectively.

It is preferable that the film 76 includes at least one kind of elementselected from the group consisting of B, Mg, Al, Si, Ca, Cr, Y, Zr, Ta,Ce and Nd, and, to be more specific, at least one kind of ceramicselected from the group consisting of B₄C, MgO, Al₂O₃, SiC, Si₃N₄, SiO₂,CaF₂, Cr₂O₃, Y₂O₃, YF₃, ZrO₂, TaO₂, CeO₂, Ce₂O₃, CeF₃ and Nd₂ O₃. Inthis case, it is desirable that the film 76 is of a thickness rangingfrom 50 to 300 μm. Further, the same material as in the first examplecan be used as the base material 71.

The sealing-treated portion 76 a can be formed by sealing by employingan exactly same resin sealing or sol-gel method as executed on thebarrier coat layer 74 in the first example. As described above, byforming the sealing-treated portion 76 a, the gas or the cleaning fluidinfiltrating through the fine holes of the film 76, i.e., the thermallysprayed film, can be effectively blocked, so that the base material 71can be protected sufficiently. Because the sealing-treated portion 76 ais for preventing the gas or the cleaning fluid from reaching the basematerial 71, any one of those shown in FIGS. 4A to 4C can be effective.However, forming the sealing-treated portion 76 a on the side of aportion of the film 76 making a contact with the base material 71 asshown in FIG. 4A is more preferable. That is, if the internal member ofthe processing vessel whose thermally sprayed film has undergone thesealing treatment is used in a plasma atmosphere obtained by applyinghigh frequency power in a high vacuum area (e.g., 13.3 Pa), a dilutedorganic solvent (e.g., ethyl acetate) in a sealing material may beevaporated, or the sealing material may be corroded by the plasma, theprocessing gas and the like, so that air pores (fine holes) may beformed in the thermally sprayed film again. Due to these air pores,surface state (e.g., temperature and adhesion state of a by-product) ofthe internal member of the processing vessel is changed with time, sothat it is possible to exert baleful influence on the process in theprocessing vessel. Thus, as shown in FIG. 4A, by avoiding to perform thesealing treatment on the surface side portion of the film 76, surfacedegradation of the film 76 may be suppressed and the process can beexecuted stably. Additionally, the sealing-treated portion 76 a may beformed, for example, in the middle of the film 76, without limiting thepositions to those depicted in FIGS. 4A to 4C. It is desirable that thesealing-treated portion 76 a is from 50 to 100 μm thick.

Also in this example, as shown in FIG. 5, exactly the same anodicoxidized film 75 as in the first example can be formed between the basematerial 71 and the film 76. Further, in this case, sealing the anodicoxidized film 75 is preferable and the same metal salt sealing asmentioned above is available for this sealing treatment.

Hereinafter, a third example will be described.

In the third example, as shown in FIGS. 6A and 6B, a film 77 is formedon the surface of the base material 71 by the thermal spraying ofceramic, the film 77 has a two-layer structure including a first ceramiclayer 78 and a second ceramic layer 79, and a sealing portion is formedin at least a portion of at least one of them. In the example of FIG.6A, a sealing-treated portion 78 a is formed in the first ceramic layer78 located at a surface side, and in the example of FIG. 6B, asealing-treated portion 79 a is in the second ceramic layer 79 locatedat a base material 71 side.

Both the first ceramic layer 78 and the second ceramic layer 79, beingincluded in the film 77, include at least one kind of element selectedfrom the group consisting of B, Mg, Al, Si, Ca, Cr, Y, Zr, Ta, Ce andNd, and, to be more specific, include at least one kind of ceramicselected from the group consisting of B₄C, MgO, Al₂O₃, SiC, Si₃N₄, SiO₂,CaF₂, Cr₂O₃, Y₂O₃, YF₃, ZrO₂, TaO₂, CeO₂, Ce₂O₃, CeF₃ and Nd₂O₃ ispreferable. In this case, it is desirable that the film 77 is from 50 to300 μm thick. Further, exactly the same material as in the first examplecan be used as the base material 71.

The sealing-treated portions 78 a and 79 a may be formed by employingexactly the same resin sealing or sol-gel method as executed on thebarrier coat layer 74 of the first example. As described above, byinstalling the sealing-treated portions 78 a and 79 a, the gas or thecleaning fluid infiltrating through the fine holes of the first andsecond ceramic layers 78 and 79, i.e., the thermally sprayed films, canbe effectively blocked, so that the base material 71 can be protectedsufficiently. Because the sealing-treated portions 78 a and 79 a areused for preventing the gas or the cleaning fluid from reaching the basematerial 71 as described above, positions of the sealing-treatedportions 78 a and 79 a are not limited as long as their functions can berealized effectively, and the whole layer may also be used as thesealing-treated portion. Further, the sealing-treated portion may beformed in both sides of the first and second ceramic layers 78 and 79.It is desirable that the sealing-treated portions 78 a and 79 a are from50 to 100 μm thick.

As described above, since, by allowing the film 77 formed on the basematerial 71 to have the two-layer structure, materials of these twolayers can be appropriately selected in accordance with the requiredcorrosion resistance and barrier property, it can be widely applied witha very high degree of freedom by performing the sealing treatment at adesired position. For example, the corrosion-resistance and the barrierproperty can be much enhanced if Y₂O₃ is used as the first ceramic layer78 located toward the surface, YF₃ or Al₂O₃ is used as the secondceramic layer 79 located toward the base material 71 and the sealing isexecuted in at least a portion of the second ceramic layer 79.

As shown in FIG. 7, in this example, exactly the same anodic oxidizedfilm 75 as in the first example may be formed between the base material71 and the film 77. Further, in this case, sealing the anodic oxidizedfilm 75 is preferable, wherein the same metal salt sealing and the likeas mentioned above and the like are available.

In order to confirm the above description, following samples wereprepared; a first sample was made by forming a thermally sprayed film ofY₂O₃ on a base material of Al alloy, a second sample was made by forminga thermally sprayed film of Y₂O₃ through a resin (PTFE) barrier coatlayer on a base material of Al alloy; and a third sample was made byforming a thermally sprayed film of Y₂O₃ on a base material of Al alloyand sealing some of the thermally sprayed film with the resin. Then, thesurface states of the thermally sprayed films were subject under plasmaenvironment after dropping a HF solution on the surfaces of the first tothe third samples to compare with each other. To be more specific, thesamples were put under a plasma atmosphere of a CF-based gas for threeminutes after dropping a 38% HF solution of 10 μl on each surface of thesamples and being heated at 50° C. for three hours. As a result, it wasfound that a crack had developed on the whole surface of the firstsample on which a countermeasure for peeling off of the thermallysprayed film had not been executed, while no crack had developed and thesurfaces of the base materials were protected by preventing theinfiltration of the processing gas and the cleaning fluid in the secondsample where the barrier coat layer was formed between the base materialand the thermally sprayed film and the third sample where some of thethermally sprayed film was sealed by the resin.

Embodiment 2

In a case where Al₂O₃ and Y₂O₃ are used in the wall member and otherinternal member of the plasma processing vessel, various problems occursince a large amount of water is absorbed due to high reactivity onwater in the air when the vacuum chamber, i.e., the processing vessel,is open to atmosphere or undergoes the wet cleaning. However, thepresent inventors have found in their investigation that these problemscan be solved by performing hydration treatment on ceramic, such asY₂O₃, including an element of the Group 3a in the periodic table orforming a hydroxide including these elements.

Based on the above description, in the members within the vacuum chamber2 in accordance with the second embodiment of the invention, i.e., theinternal members of the plasma processing vessel, such as the depositionshield 2 a, the exhaust plate 44, the focus ring 43, the shower head 3,the mounting table 4, the electrostatic chuck 42 and the inner-wallmember of the vacuum chamber 2 in FIG. 1, a hydrated portion is formedof ceramic including the element of the Group 3a in the periodic table,or at least a portion of that is formed of hydroxide including thatelement.

In the internal member of the plasma processing vessel made in this way,release of water hardly occurs during the plasma process since thestructure makes it difficult to adsorb water and release watertherefrom.

First, in a first example, as shown in FIG. 8, a film 82 made of ceramicincluding an element of the Group 3a in the periodic table is formed ona base material 81 and a hydration-treated portion 82 a is formed, forexample, at least in a surface portion of the film 82.

Various types of steel including stainless steel (SUS), Al, Al alloy, W,W alloy, Ti, Ti alloy, Mo, Mo alloy, carbon, oxide and non-oxide basedsintered ceramic body, carbonaceous material and the like are usedproperly for the base material 81 in a similar manner to the basematerial 71.

The film 82 may be made of ceramic including an element of the Group 3ain the periodic table, but it is preferable to be made of oxideincluding the element of the Group 3a in the periodic table. Further,among these, Y₂O₃, CeO₂, Ce₂O₃ and Nd₂O₃ are preferable and, among them,Y₂O₃ is particularly desirable since it has been conventionally andwidely used and has high corrosion resistance.

The film 82 can be formed preferably by employing a technique forforming a thin-film such as the thermally sprayed method and the PVD andCVD method. Further, it is possible to form the film by employing theimmersion method, the coating method or the like.

The hydration-treated portion 82 a can be formed, for example, by makingthe film 82 react on water vapor or high temperature hot water to causea hydration reaction. In case of using Y₂O₃ as the ceramic, the reactionsuch as an equation (1) below occurs:Y₂O₃+H₂O→Y₂O₃·(H₂O)n→2(YOOH)→Y(OH)₃  (1)

wherein mantissa is not considered in Eq (1).

As represented in the equation (1), by the hydration treatment, Yhydroxide is formed in the end. In case of another element of the Group3a in the periodic table, such hydroxide is formed by almost the samereaction. Y(OH)₃, Ce(OH)₃ and Nd(OH)₃ are preferable for such hydroxide.

In order to confirm this, samples having the thermally sprayed film ofY₂O₃ on the base material were prepared, and X-ray diffractionmeasurement was performed on the one sample which was hydrated byimmersion in high temperature hot water maintained at a temperature of80° C. for 150 hours and then dehydrated at room temperature, and onanother sample on which these treatments were not performed. Thecomparison result showed that Y(OH)₃ was detected only in the sample onwhich the hydration treatment was performed, confirming that hydroxidewas formed by the hydration treatment, as shown in FIGS. 9A and 9B.

The hydroxide of the element of the Group 3a in the periodic table ishighly stable and has features that chemically adsorbed water isdifficult to be released and it is difficult to adsorb water. Theproblem caused by water during the process can be avoided by forming thehydroxide like this by the hydration treatment.

In order to confirm an effect of the hydration treatment, afterpreparing samples which had a 200 μm thick film of thermally sprayedY₂O₃ on the base material, one sample was treated by boiling water forthree hours, while another sample was not treated by boiling water. IPAwas sprayed on both of them. IPA spraying becomes an acceleration testsince IPA has higher adsorption than water. The test showed that IPA wasadsorbed to the non-hydrated sample but no adsorption occurred to thehydrated sample, as shown in FIG. 10. From this, it was confirmed thatthe hydration treatment made it difficult for adsorption to occur.

Next, in the same way, after preparing samples which had a 200 μm thickfilm of thermally sprayed Y₂O₃ on the base material, a sample wastreated by boiling water for three hours while another sample was nottreated by boiling water. Both of them were coated by the resin and cutto check cross sections thereof. The result, depicted in FIGS. 11A and11B, showed that there were no differences on the surface states of theboth samples. However, for the sample without the treatment, the filmwas transparent on the whole, confirming that the resin penetratedthrough the whole film. On the other hand, for the treated sample, onlysmall portion close to the surface was transparent and the inside waswhite in the treated sample, indicating that the resin was hardlypenetrated to the inside of the treated sample. That verifies that thehydration treatment causes hydrophobic property. Further, as shown inFIG. 11C, when the film about 20 μm thick from the surface was removedafter the hydration treatment, it was found that the removed portion wastransparent and hydrophobic property was reduced.

Moreover, an effect of H₂O on a Y₂O₃ surface has been described indetail in a paper entitled “Specific Adsorption Behavior of Water on aY₂O₃ Surface” of Kuroda et al. disclosed on pages 6937 to 6947 ofLangmuir, Vol. 16, No. 17, 2000.

Hereinafter, the hydration treatment will be described in detail.

The hydration treatment can be executed by heat treatment in anenvironment containing abundant water vapor or treatment in boilingwater. Several water molecules can be attracted toward neighborhood of,e.g., an yttrium oxide (Y₂O₃) molecule to be combined together into onestable molecule cluster. At this time, main parameters include partialpressure of water vapor, temperature and time of heat treatment and thelike. For example, a stable hydroxide can be formed by heat treatmentfor about 24 hours in a furnace with temperature ranging from about 100to about 300° C. under relative humidity which is equal to or greaterthan 90%. If relative humidity and temperature of heat treatment arelow, it is preferable to prolong the time of treatment. Treatment athigh temperature and high pressure is desirable for efficient hydrationtreatment. Because the hydration reaction on the surface of yttriumoxide can proceed basically even at room temperature if executed for along time, the same final state can be obtained also under otherconditions besides the above condition. Further, in the hydrationtreatment, using water including ion (alkali water with a pH higher than7) results in a hydroxide with a better hydrophobic property than forthe case using pure water.

Furthermore, not limited to the hydration treatment, other methods, forexample, forming hydroxide at a raw material step, may be employed aslong as the hydroxide is formed finally. In case of making the film bythe thermal spraying method, because the raw material is exposed to hightemperature, there is a concern that the hydroxide may be changed intoan oxide if hydroxide is formed at the raw material step, but, even inthis case, a hydroxide film can be formed by thermally spraying under acondition of high humidity. Instead of forming the hydration-treatedportion like this, the hydroxide may be formed directly by using adifferent method.

The hydration-treated portion or hydroxide layer should be formed in asurface portion of the film 82 in order that the film 82 has a structuredifficult to adsorb water and be released from water. It is desirablethat the hydration-treated portion or hydroxide film of this case isequal to or greater than 100 μm thick and the thickness thereof is setoptimally depending on usage place.

Densification is also promoted by the hydration treatment for theceramic including the element of the Group 3a in the periodic table. Forexample, the Y₂O₃ film formed by the thermal spraying is porous beforethe hydration treatment as shown FIG. 12A, but it is densified by thehydration treatment as shown in FIG. 12B. By becoming dense like this,the same barrier effect as in the first embodiment is obtained inaddition to the above effect.

In view of obtaining only the barrier effect, the hydration-treatedportion 82 a of the hydroxide formed by the hydration treatment need notbe located necessarily in the surface portion of the film 82, and it maybe formed at any position of the film 82. In a case of forming thehydroxide layer of the hydroxide formed by another method, it isdesirable to perform the sealing by the resin or sol-gel method asmentioned above. In this example, in a similar way to the firstembodiment, as depicted in FIG. 13, exactly the same anodic oxidizedfilm 83 as in the first embodiment may be formed between the basematerial 81 and the film 82. Further, it is preferable to perform thesealing treatment on the anodic oxidized film 83 in a similar way to thefirst embodiment, and, as this sealing treatment, the metal salt sealingidentical to the aforementioned one is available.

Hereinafter, a second example will be described.

In the second example, as shown in FIGS. 14A and 14B, a film 84 isformed in the surface of the base material 81, it has two-layerstructure including a first ceramic layer 85 and a second ceramic layer86, and a hydration-treated portion is formed in at least a portion ofat least one of the first and the second ceramic layer. Ahydration-treated portion 85 a is formed in a surface side of the firstceramic layer 85 in the example of FIG. 14A, and a hydration-treatedportion 86 a is formed in a side of the second ceramic layer 86 making acompact with the base material 81 in the example of FIG. 14B.

Both the first ceramic layer 85 and the second ceramic layer 86 includedin the film 84 are formed of ceramic including an element of the Group3a in the periodic table and, an oxide including an element of the Group3a in the periodic table is preferable. Among them, Y₂O₃, CeO₂, Ce₂O₃and Nd₂O₃ are preferable, and particularly, Y₂O₃ is preferable.Furthermore, exactly the same material as in the first example can beused as the base material 81.

These first and second ceramic layers 85 and 86 can be formedpreferably, in a similar way as the film 82 in the first example, byemploying the technique for forming a thin-film such as the thermalspraying method, the PVD method or the CVD method. Further, it ispossible to form them by employing an immersion method, a coatingmethod, or the like.

The hydration-treated portions 85 a and 86 a can be formed in exactlythe same way as the hydration-treated portion 82 a in the first example.If the hydration-treated portion is disposed in the surface portion ofthe film 84 as shown in FIG. 14A, a structure making adsorbing water orbeing released from water difficult can be formed, and, if thehydration-treated portion is in the film 84, as shown in FIG. 14B, thebarrier effect can be made work effectively. In order to form thehydration-treated portion in the film 84, after fabricating the secondceramic layer 86 on the base material 81, the hydration treatment isperformed and the first ceramic layer 85 is formed. It is desirable thatthe hydration-treated portions 85 a and 86 a are of thickness equal toor greater than 100 μm.

By forming the film 84 on the base material 81 in the two-layerstructure like this, it can widen the scope of its applicability withlarge degree of freedom, since materials of the two layers and positionof the hydration treatment can be selected to better accommodate variousspecific requirements of the situation.

In this example, the same anodic oxidized film 83 as in the firstexample may be formed between the base material 81 and the film 84, asshown in FIG. 15.

Hereinafter, a third example will be described.

In the third example, as shown in FIG. 16, a film 87 is formed on thesurface of the base material 81, and it has a first ceramic layer 88formed of ceramic including at least one kind of element of the Group 3ain the periodic table; and a second ceramic layer 89 formed by thermalspraying of ceramic, wherein a hydration-treated portion 88 a formed ina surface portion of the first ceramic layer 88.

As the ceramic of the first ceramic layer 88 including the element ofthe Group 3a in the periodic table, the oxide including the element ofthe Group 3a in the periodic table is preferable. Among them, Y₂O₃,CeO₂, Ce₂O₃ and Nd₂O₃ are preferable and Y₂O₃ is particularlypreferable. It is desirable that the first ceramic layer 88 is ofthickness ranging from 100 to 300 μm. The first ceramic layer 88 can beformed preferably, in a similar way to the film 82 in the first example,by employing the technique for forming a thin-film such as the thermallyspraying method, the PVD method and the CVD method. Further, it ispossible to form the layer by employing the immersion method, thecoating method, or the like.

It is preferable that the second ceramic layer 89 includes at least onekind of element selected from the group consisting of B, Mg, Al, Si, Ca,Cr, Y, Zr, Ta, Ce and Nd, and, to be more specific, at least one kind ofceramic selected from the group consisting of B₄C, MgO, Al₂O₃, SiC,Si₃N₄, SiO₂, CaF₂, Cr₂O₃, Y₂O₃, YF₃, ZrO₂, TaO₂, CeO₂, Ce₂O₃, CeF₃ andNd₂O₃. It is desirable that the second ceramic layer 89 is of thicknessranging from 50 to 300 m. Further, exactly the same material as in thefirst example can be used as the base material 81.

The hydration-treated portion 88 a can be formed in the same way as thehydration-treated portion 82 a in the first example. Because thehydration-treated portion is formed in the surface portion of the film87, the film 87 can be made to have a structure difficult to adsorbwater and release water. In addition, the barrier effect may be madework effectively by forming the hydration-treated portion 88 a insidethe first ceramic layer 88. It is desirable that the hydration-treatedportion 88 a is of thickness equal to or greater than 100 μm.

As shown in FIG. 17, it is preferable to form a sealing-treated portion89 a in the second ceramic layer 89. The sealing-treated portion 89 acan be formed by using the same resin sealing or sol-gel method asdescribed in the above-mentioned first embodiment. The base material 81can be protected sufficiently by installing the sealing-treated portions89 a since the gas or the cleaning fluid infiltrating through fine holesof the second ceramic layer 89, i.e., the thermally sprayed film, can beblocked effectively. Further, the sealing-treated portion 89 a can beformed at any position of the second ceramic layer 89.

By forming the structures as shown in FIGS. 16 and 17, the film 87 canhave a structure difficult to adsorb water and release water by thehydration-treated portion 88 a of the first ceramic layer 88,simultaneously having excellent corrosion-resistance. Besides, the basematerial 81 can be protected effectively by the barrier effect of thesecond ceramic layer 89. Particularly, in the structure shown in FIG.17, the existence of the sealing-treated portion 89 a can furtherenhance the barrier effect.

Moreover, as shown in FIG. 18, the first ceramic layer 88 and the secondceramic layer 89 may be installed in a reversed order. In this case,protection effect on the base material 81 may be improved since thehydration-treated portion 88 a of the first ceramic layer 88 laid outnext to the base material 81 can enhance the barrier effect effectually.

In this example, as shown in FIG. 19, the same anodic oxidized film 83as in the first example may be formed between the base material 81 andthe film 87.

Hereinafter, the Third Embodiment will be Described

In the internal member of the plasma processing vessel in accordancewith this embodiment, as shown in FIG. 20, a hydration-treated portion91 is formed in a surface portion of a sintered ceramic body 90including the element of the Group 3a in the periodic table. Thehydration-treated portion 91 can be formed in the same manner as in thesecond embodiment, and the hydration treatment generates the hydroxideincluding the element of the Group 3a in the periodic table.

The hydration-treated portion 91 is formed in the surface portion, sothat a structure making it difficult to adsorb water or release water isformed. It is desirable that the hydration-treated portion 91 or thehydroxide film of this case is of thickness equal to or greater than 100μm.

In this embodiment, as in the second embodiment, ceramic including anelement of the Group 3a in the periodic table or oxide including anelement of the Group 3a in the periodic table. Among them, Y₂O₃, CeO₂,Ce₂O₃ and Nd₂O₃ are preferable and, in particular, Y₂O₃ is desirable.

Additionally, the present invention is not limited to the aboveembodiments and various changes and modifications can be made. Forexample, in the above embodiments, the case of applying the presentinvention to the internal members of the plasma processing vessel of aparallel plate plasma etching apparatus of a magnetron type using apermanent magnet, i.e., the deposition shield 2 a, the exhaust plate 44,the focus ring 43, the shower head 3, the mounting table 4, theelectrostatic chuck 42, and the inner wall member of the vacuum chamber2 has been described as an example, but the present invention is notlimited to the apparatus of this structure, and can be applied tointernal members of the plasma processing vessel used in a parallelplate plasma etching apparatus having no magnetron; another plasmaetching processing apparatus and etching apparatus such as aninductively coupled one; an apparatus executing various plasma processessuch as an ashing and a film forming process in addition to etching; anda plasma processing apparatus executing the process on a glass substratefor LCD as well as a semiconductor wafer.

The internal member of the plasma processing vessel in accordance withthe present invention is desirable for a plasma process in anenvironment of high corrosion, in particular, since the film formed onthe base material is formed of ceramic with high corrosion resistanceand a portion is formed to function as a barrier. Further, it ispreferable as an internal member of a plasma processing vessel with aproblem of water, because its structure is stable against water byexecuting the hydration treatment on the ceramic including an element ofthe Group 3a in the periodic table.

In accordance with the present invention, in internal members of aplasma processing vessel of a structure having a base material and afilm formed by thermal spraying, peeling off of the film formed bythermal spraying is suppressed since a surface of the base material isnot exposed to a processing gas or a cleaning fluid by preparing severallayers functioning as a barrier.

Further, in accordance with the present invention, an internal member ofa plasma processing vessel which is difficult to release water in plasmaprocess can be obtained, because a structure making it difficult toadsorb water and release water is formed by performing the hydrationtreatment on the ceramic including at least one kind of element of theGroup 3a in the periodic table, or by forming a layer or sintered bodyhaving the hydroxide including at least one kind of element of the Group3a in the periodic table.

While the invention has been shown and described with respect to thepreferred embodiments, it will be understood by those skilled in the artthat various changes and modifications may be made without departingfrom the spirit and scope of the invention as defined in the followingclaims.

1. An internal member of a plasma processing vessel, comprising: a basematerial comprising at least one of stainless steel, Al, Al alloy, W, Walloy, Ti, Ti alloy, Mo, Mo alloy, carbon, oxide or non-oxide basedsintered ceramic body, and carbonaceous material, the base materialbeing an object on which a film is to be constructed; and a film formedon a surface of the base material, wherein the film has a main layerformed by thermal spraying of ceramic and a barrier coat layer formed ofceramic including an element selected from the group consisting of B,Mg, A1, Si, Ca, Cr, Y, Zr, Ta, Ce and Nd, wherein the barrier coat layeris an intermediate layer formed between the main layer and the basematerial, and wherein the barrier coat layer is a thermally sprayed filmand at least parts of pores inside the barrier coat layer are sealed bya resin provided at a lower portion of the barrier coat layer includinga surface contacted with the base material and not including a surfacecontacted with the main layer; wherein the main layer and the barriercoat layers are separate layers.
 2. The internal member of claim 1,wherein the barrier coat layer is formed of at least one kind of ceramicselected from the group consisting of B₄C, MgO, Al₂O₃, SiC, Si₃N₄, SiO₂,CaF₂, Cr₂O₃, Y₂O₃, YF₃, ZrO₂, TaO₂, CeO₂, Ce₂O₃, CeF₃ and Nd₂O₃.
 3. Theinternal member of claim 1, wherein the resin is selected from the groupconsisting of SI (silicone), PTFE (polytetrafluoroethylene), PI(polyimide), PAI (polyamideimide), PEI (polyetherimide), PBI(polybenzimidazole) and PFA (perfluoroalkoxyalkane).
 4. The internalmember of claim 1, wherein the main layer is formed of at least one kindof ceramic selected from the group consisting of B₄C, MgO, Al₂O₃, SiC,Si₃N₄, SiO₂, CaF₂, Cr₂O₃, Y₂O₃, YF₃, ZrO₂, TaO₂, CeO₂, Ce₂O₃, CeF₃ andNd₂O₃.
 5. The internal member of claim 1, wherein an anodic oxidizedfilm is formed between the base material and the film, and wherein atleast parts of pores inside the anodic oxidized film are sealed by asecond resin selected from the group consisting of SI (silicone), PTFE(polytetrafluoroethylene), PI (polyimide), PAI (polyamideimide), PEI(polyetherimide), PBI (polybenzimidazole) and PFA(perfluoroalkoxyalkane).
 6. The internal member of claim 5, wherein thesealing treatment is executed by using an element of the Group 3a in theperiodic table.
 7. The internal member of claim 5, wherein the mainlayer is formed of at least one kind of ceramic selected from the groupconsisting of B₄C, MgO, Al₂O₃, SiC, Si₃N₄, SiO₂, CaF₂, Cr₂O₃, Y₂O₃, YF₃,ZrO₂, TaO₂, CeO₂, Ce₂O₃, CeF₃ and Nd₂O₃.
 8. The internal member of claim1, wherein an anodic oxidized film is formed between the base materialand the film, and pores in the anodic oxidized film are sealed by anaqueous solution of metal salt.
 9. The internal member of claim 1, ablast process is performed on the surface of the barrier coat layer toimprove adhesivity with the main layer.